Your mod looks great, nice craftsmanship! I think the goal is to have the air flow smoothly with as few disruptions as possible. Do you have any plans to extend it toward the back of the car?
Looking at the pictures you posted, I think I would cut a channel for the exhaust if it would allow the back of the plate to line up directly with the floorpan. (From the side view it looks like the whole thing is angled down to clear the exhaust pipe) A cut-out section would keep the exhaust from rattling or vibrating on the pan and allow dissipation of some exhaust heat.
Keep us posted on the progress.